One key item to remember is that boards are not really going to be the size you are buying. Take a 2 x 4. A 2 x 4 use to mean that a board was truly 2″ by 4″. Now a 2 x 4 is really 1.5″ x 3.5″. The length of a board doesn't change, so when you buy an 8′ board it usually is 8′.
Another important idea to lay out right now is the difference between Board Foot and Linear Foot. A linear foot is used mostly by home improvement centers for pine and only references to the length of the board. A board foot is different. The standard board foot is 1″ thick by 12″ wide by 12″ long. To determine a board foot you must multiply the width by the thickness then times the length. Take this number and divide it by 12 and this will give the board feet.
Types of Wood
There is basically two type of lumber; softwood and hardwood. All softwoods come from “evergreens.” Hardwood trees have broad leaves that fall off in the fall. Softwood has a closed grain structure, while hardwood has an open grain. Softwood is soft and can be easily dented with a fingernail, while hardwood tends to resist dents. Softwood tends to be cheaper because the tree grows faster than hardwood trees, basic supply and demand are at work here.
Two boards of the same type of tree can have a very different look. The reason being is grain structure. Grain structure can have a significant impact on your project. Straight grain is said to be the strongest, while a grain that varies would be more beautiful for a table project. A tight or close grain structure will be stronger than a wide or lose grain. If you are putting two pieces of wood together, always remember to cross or alter the grain to make it stronger.
Common Grades of Wood
Grade doesn't give you the total quality of the board, it gives you the number of defects in a board.
|Clear||Has No Knots|
|Select||High quality wood and this is broken down even further into No.1, No.2, No.3 or A,B,C,D. The lower you go the more knots it has. No.1 would be better than No.3.|
|No.2 Common||Has tight knots, no major blemishes and would be ideal for shelving|
|No. 3 Common||Some knots may be loose, often damaged or blemished|
|Construction||Good Strength and is used for general framing|
|Utility||Economy grade and would be used for rough framing.|
Since lumber is natural, no one piece is going to be the same. When you choose your lumber, sometimes you will see defects. Some common defects are:
|Twist||Multiple Bends in the board|
|Bow||Warp on the face of a board from end to end|
|Cup||Hollow across the face and the sides are bent up a little|
|Crook||Warp along the edge line and also known as a crown|
|Split||A crack going down the board that goes all the way through|
|Check||Crack along the annual growth rings, but doesn't pass through the wood|
|Shake||Separating of grain between the growth rings|
|Knot||A knot looks like a dark circle and is caused by a branch that grew in that spot|
Picking the Lumber
Remember the most important aspects to a good project is getting the right wood. After you know what type of wood and what size you want, you will need to pick through the wood. Don't feel that you have to get the top pieces of wood. Dig through the pile till you find the ones you want. Put the lumber on the floor to make sure it doesn't have any defects. Also eye the lumber down the side to see if it is bent.
Remember wood moves with humidity and temperature. If you plan on building something, I would suggest buying the lumber and letting it sit in your shop for at least two weeks before you even make a cut. Try to keep the humidity low and keep your wood flat.